1. Field of the Invention
The present invention relates to the separation of solids from liquids. In particular, the present invention relates to separating floating solids, such as plastic debris, from the surface of a moving liquid stream, such as water in a waterway, and conveying the floating solids to the side of the liquid stream by a screw type conveyor.
2. Prior Art
Containment booms have been used for the containment and control of petroleum spills. These devices typically keep the petroleum spill from dispersing on the water's surface, containing the spilled material for removal. These booms are typically portable and are deployed around a spill.
Floatable objects are driven along waterways--such as storm culverts, flood control channels, and natural streams--by the forces of stream flow, tidal action and wind forces. Once floatables have moved from the confines of the waterway stream, flow forces are subordinate to tidal and wind forces. Inevitably the vast majority of the floatables are deposited on beaches and shores neighboring the waterway outlet. Floatables deposited on shores and beaches represent a nuisance and a health threat to humans using these resources. Decomposing floatables also damage the marine life. Floatables which are not deposited on shores foul marine equipment, presenting a hazard to navigation.
Boom systems are associated with petroleum spills and containment. Containment booms that remove floatables are typically comprised of large mesh nets strung across the waterway to catch floatables on the net structure. These devices are ineffective, as once the net mesh becomes plugged with floatables, the net's resistance to water flow causes an increase in hydraulic drag force on the net. This increased drag force damages the net or causes the net to be displaced vertically from the path of the stream flow. Moreover, the floatables entrapped in the net are difficult to remove from the net and are frequently released into the waterway during the removal operation.
Log booms are used to collect large floating objects swept down waterways. They are not effective in removing or containing light floatables, which tend to be driven over the top of the log boom. Petroleum booms of various sizes, shapes and construction methodologies used in petroleum containment are also ineffective in containing and entrapping floatables.
Existing boom systems primarily contain pollutants, usually petroleum products for subsequent removal from the containment system. The helix boom is unique in that in addition to containing the floatables, it removes them from the water by transporting them to the waterway side for collection and subsequent removal the collected floatables.